Campaigners presented a petition of more than a million signatures to the EU executive on Thursday, demanding a halt to approvals of new genetically modified (GM) crops.
The petition is seen as a test case for the "European citizen's initiative," introduced under the EU's new constitutional treaty, which enables a million or more people to jointly ask the European Commission to change EU legislation.
Organized by environmental campaigners Greenpeace, the petition calls on the Commission to stop approving GM crops and set up a new scientific body to study the impact of the technology and determine regulations.
It follows the Commission's decision in March to grant the first EU GM cultivation approval in 12 years for the "Amflora" potato.
"Over a million people across Europe have set the EU a democratic test -- will the EU address the real concern people have about GM crops and food, or will it side with the chemical industry lobbyists controlling GM technology?" Greenpeace's EU Director Jorgo Riss said.
"Until safety issues of GMs are examined by independent experts, all GM authorizations should stop."
Detailed rules for how the citizen's initiative will work are currently being finalized by EU governments and lawmakers, and are not expected to be in force until the end of next year, at the earliest.
As a result, the Commission has said the petition cannot officially be regarded as a European citizen's initiative, as the signatures were collected before the rules have been finalized.
A spokesman for the EU executive said it would treat the signatures "as a petition in the spirit of the citizen's initiative."
John Dalli, the EU commissioner responsible for GM policy, said: "I am committed to look seriously at the request made through this initiative."
Under draft rules for the initiative agreed by EU governments and lawmakers earlier this week, the Commission would have three months from receipt of a petition to decide what action to take.
This could include drafting new legislative proposals or taking other policy initiatives, but after considering a petition the Commission could also choose to ignore any requests for changes to EU rules.
GM crops are one of the most controversial areas of EU policy, with widespread public opposition to the technology in most EU countries.
Earlier this year the Commission proposed an overhaul of EU rules on GM cultivation, which would let governments decide individually whether or not to grow the technology, and Dalli pledged to press ahead with EU approvals while the plans are discussed.